Weighing in at No. 9 is Giraffitian brancai. Its mass was calculated to be 37.5 tons.

Girth is only one component of size, but the longest dinosaurs tended also to be the heftiest. Lacovara said many such dinosaurs spent their days pursuing “a life-long obsession with eating.” Dinosaurs like Giraffitian would devote hour after hour to consuming tree and fern leaves, not moving much from their feasting spots.

Weighing in at 62 tons is Brachiosaurus altithorax, which was hailed as “the largest-known dinosaur” by discoverer Elmer Riggs in 1903. While it’s No. 5 on the list now, at 62 tons, this dinosaur still made the top 10.

Sauroposeidon proteles was not included in the Scientific Reports study. This species, and the entire genus, are only known from several incomplete specimens. So it's more challenging to accurately estimate its weight and height. Some paleontologists theorize that it weighed anywhere from 55-66 tons. It could, therefore, move even higher on this list should more fossils be found.

Lacovara and a team of his colleagues discovered Paralititan stromeri in 2001. “We only recovered the humerus of Paralititan, and therefore cannot be sure about its limb proportions,” Lacovara told Discovery News.

Based on the fossil that was excavated, however, it was an enormous dinosaur. The humerus, measuring about 5 1/2 feet, is lengthier than that of any other known Cretaceous sauropod. Paralititan is another contender for possible top spot placement on this list if additional fossils are found and support the speculation about its size.

“Dreadnoughtus schrani has the largest reliably calculable weight of any known land animal,” Lacovara said. Announcement of its discovery was made just this week, reminding that on any day, new fossil finds could change this list.

The mass of Dreadnoughtus was 65.4 tons. This dinosaur had no known enemies during its lifetime.

Most paleontologists, including Lacovara, believe that Argentinosaurus huinculensis was the world’s largest-ever land animal. “I think it is very likely that Argentinosaurus is the most massive dinosaur yet known," Lacovara said. "However, I don’t think we can make a reliable estimation of its mass.”

He explained that the femur sometimes associated with this species has never formally been referred to in a peer-reviewed journal. Rough estimates by others estimate that Argentinosaurus could have been 115 feet in length with a weight of anywhere from 88–110 tons.